Originally Posted by Cowboy T
Trim handgun brass? No way. Rifle? Yup.
^^ This, straight-wall pistol cases don't stretch so trimming is not needed for semi-auto cartridge ammo. I have loaded both one batch and mixed batch pistol cases (9x19, 9x21 and .38 super) and crimp is not effected, no die changes needed. In fact, you really aren't crimping on a straight-wall pistol case used in semi-autos, all you are doing is removing the case mouth belling added to seat the bullet easily. This is done using a taper crimp die and that is very insensitive to small case length changes.
If you are roll crimping for rimmed pistol cases like .38 special, .357M and .44M, then you do want case length uniformity and trimming may help some here. I only use one batch cases for my .44M loading and don't need to trim as length is too close to matter.